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The three sections shown highlighted in the previous diagram (and repeated in the next diagram) are those that implement ASP+ itself, and which we're interested in for this book: |
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Together, these three sections implement the Web Application Infrastructure – the topic that we are concerned with in this book. Together with the new runtime framework, it provides a range of exciting new features:
User Interface Support
As part of the ASP+ libraries, there is a host of intelligent server-based rich controls for building Web-based user interfaces quickly and simply. They can output HTML 3.2 code for down-level browsers, while taking advantage of the runtime libraries for enhanced interactivity on richer clients such as Internet Explorer 4 and above.
These server-based controls can be also be reused to build controls composed of other controls, inheriting implementation and logic from these constituent controls.
Data Access Support
The NGWS framework provides a new version of ADO, called ADO+, which offers integrated services for accessing data – regardless of the format or location of that data. ADO+ presents an object-oriented view of relational data, giving developers quick and easy access to data derived from distributed sources.
ADO+ also improves support for, and to some extent relies on, XML. ADO+ can automatically persist and restore recordsets (or datasets as they are now called) to and from XML. As we'll see, this is particularly useful when passing data around the Web using ASP+ Web Services.
Scalability for Distributed Applications
Two of the major requirements for any Web-based application are a robust operating platform, and scalability to allow large numbers of multiple concurrent requests to be handled. The NGWS runtime provides these features by allowing automatic error and overload detection to restart and manage the applications and components that are in use at any one time. This prevents errant code or memory leaks from soaking up resources and bringing the server to a halt.
There are also new and updated system and infrastructure services, including automatic memory management and garbage collection, automatic persistence and marshaling, and evidence based security. Together these features provide for more scalable and reliable resource allocation and application processing.
Existing Software and Training Investments
Despite all the changes to the core operating system and runtimes, great care has been taken to maintain backward compatibility with earlier versions of Windows, COM and ASP. In most cases, existing applications, COM and COM+ components, ASP pages, and other scripts and executables work under the NGWS runtime. Alternatively, you can update them in your own time as your business requirements demand.
All ASP+ pages have the .aspx file extension, and this is mapped to the ASP+ runtime framework. This allows pages that have the .asp file extension to run unchanged under the existing ASP runtime.
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